1. Field of the Invention
The present invention relates to a multi-antenna module, in particular, to a built-in multi-antenna module.
2. Description of Related Art
Wireless LAN or 802.11a/b/g/n access-point antennas of the prior art are almost of external antenna structure. Common dipole antennas have a plastic or rubber sleeve covering thereon. In general, the dipole antenna is a single-band antenna for 2.4 GHz operation or a dual-band antenna for 2.4/5 GHz operation. The height of the dipole antenna is triple the thickness of the wireless broadband router/hub device, and one part of the dipole antenna is disposed on a side of the router and the rest of the dipole antenna is protruding from the top housing of the router. However, the protruded part of the dipole antenna can easily be vandalized by outside force and also occupies space, which deteriorates the aesthetic appeal of the product, especially for the multi-antenna system.
When wireless LAN applied to 2.4/5 GHz or 802.11a/b/g/n applied to a dual-band antenna, the antenna has a single signal feeding port only. Typical dual-band antenna is a dual-band access-point dipole antenna that has two radiation copper pipes and uses coaxial transmission line to achieve dual-band operation for 2.4/5 GHz operation. However, the typical dual-band antenna needs to use diplexers to simultaneously transmit and/or receive the 2.4 GHz and 5 GHz band signals to 2.4 GHz module and 5 GHz module, so that the cost would be increased and the whole system power loses extra gain. Hence, two single-band antennas are respectively operated in the 2.4 GHz and 5 GHz bands to achieve concurrent dual-band operation in order to solve the above-mentioned drawbacks.
Moreover, the prior art another provides a dual-band cross polarization dipole antenna structure that discloses a dual antenna system. The dual antenna system has two dual-band dipole antennas to generate two operating frequency bands for 2.4 GHz and 5 GHz operation. However, the antenna structure is a stack structure, so that the height of the whole antenna structure is high.
However, the above-mentioned prior art has the following common defects: 1. The traditional dipole antenna needs to use the plastic or rubber sleeve covering around the antenna, so that the cost is increased; 2. The antenna of the prior art can not be fully hidden in the router, so that the aesthetic appeal of the product that uses the antenna of the prior art is deteriorated.